Trading kidneys, repugnant markets and stable marriages win the Nobel Prize in Economics

Roth and Shapley charted a course for economists to go beyond simply arguing for markets in everything.

The 2012 Nobel Prize in Economics - technically the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel, but nobody cares - has been awarded to two American Economists, Alvin Roth and Lloyd Shapley "for the theory of stable allocations and the practice of market design". The Nobel Committee explains what that means:

This year's Prize concerns a central economic problem: how to match different agents as well as possible. For example, students have to be matched with schools, and donors of human organs with patients in need of a transplant. How can such matching be accomplished as efficiently as possible? What methods are beneficial to what groups? The prize rewards two scholars who have answered these questions on a journey from abstract theory on stable allocations to practical design of market institutions.

Lloyd Shapley used so-called cooperative game theory to study and compare different matching methods. A key issue is to ensure that a matching is stable in the sense that two agents cannot be found who would prefer each other over their current counterparts. Shapley and his colleagues derived specific methods – in particular, the so-called Gale-Shapley algorithm – that always ensure a stable matching. These methods also limit agents' motives for manipulating the matching process. Shapley was able to show how the specific design of a method may systematically benefit one or the other side of the market.

Alvin Roth recognized that Shapley's theoretical results could clarify the functioning of important markets in practice. In a series of empirical studies, Roth and his colleagues demonstrated that stability is the key to understanding the success of particular market institutions. Roth was later able to substantiate this conclusion in systematic laboratory experiments. He also helped redesign existing institutions for matching new doctors with hospitals, students with schools, and organ donors with patients. These reforms are all based on the Gale-Shapley algorithm, along with modifications that take into account specific circumstances and ethical restrictions, such as the preclusion of side payments.

Even though these two researchers worked independently of one another, the combination of Shapley's basic theory and Roth's empirical investigations, experiments and practical design has generated a flourishing field of research and improved the performance of many markets. This year's prize is awarded for an outstanding example of economic engineering.

The committee have yet again reaffirmed the old adage that the most important thing to do when trying for a nobel prize is to live long enough that your achievements are recognised. The Gale-Shapley algorithm, for instance, was devised in 1962, when Lloyd Shapley was 34. It concerns a maths problem known as the stable marriage problem: if you have an even number of men and women, can you always come up with a set of marriages where there are no two people of opposite sex who would both rather have each other than their current partners? (1960s maths problems: usually heteronormative.) If you can, then the marriage is "stable".

The Gale-Shapley algorithm is a way of always ensuring stable matches; and much of Shapley's work covers the same areas, straddling the boundaries between economics, mathematics, and computer science.

Roth is the younger of the two winners, and works in a far more empirical sphere. As the committee points out, although the two men never actually collaberated, Roth took Shapley's theoretical work and applied it to actually existing markets. For instance, Roth used the Gale-Shapley agorithm to ease the kidney shortage in the US. David Wessel explains (£):

As of noon yesterday, 58,470 people in the U.S. were waiting for a kidney transplant. Most won't get one this year. There aren't enough donated kidneys to go around. Surgeons transplanted just 15,129 kidneys last year. Now a band of transplant surgeons and economists are trying to fix that by creating a moneyless market for exchanging kidneys. Most transplanted kidneys come from a person who has died, a supply that grows slowly because of ignorance about the need for donations or grieving relatives' reluctance. But a kidney taken from a live donor works better, and almost everyone has a spare. As techniques improve for removing healthy kidneys and for suppressing the body's tendency to reject a transplant, doctors increasingly turn to kidneys from living donors, usually relatives. Last year, 43% of kidneys transplanted in the U.S. came from living donors, up from 28% a decade ago. But a biological barrier often blocks a transplant from a relative. In about a third of all would-be pairs, blood types are incompatible. In others, the sick person has antibodies that can initiate a rejection of the donated organ. It's heartbreaking "to have the treasure of the live donor and then have that not go forward because of a biological obstacle," says Massachusetts General Hospital transplant surgeon Francis DelMonico.

Occasionally, transplant centers spot a way out: One New England father with blood type A couldn't donate a kidney to his daughter with blood type B. So he gave a kidney to a teenager with blood type A, and the teenager's sister gave a kidney for the man's daughter. New England's transplant centers have done six such exchanges. Baltimore's Johns Hopkins University has done seven.

The crucial thing about Roth's work, from an economic point of view, is that it involves finding stable allocations using market-like situations without involving money. The kidney swaps in the New England situation are market-like, trading kidneys for kidneys in a way that makes all parties better-off, but they don't actually require kidneys to be bought and sold.

We can see the importance of this by looking at another paper of Roth's, not cited by the committee, on repugnance in markets (pdf). Roth demonstrates that some markets are limited because the very existance of a market in some goods is considered repugnant. He argues, for instance, that the trade in horse meat being banned in California is not done through fears that eating horse meat is unsafe; nor is it done for animal welfare reasons, since it is still legal to farm and kill horses. But banned it is, and Roth argues that the natural response of economists to situations of this type - to argue for freer markets - is wrong, since it ignores the very strong feelings involved in the situation. Instead:

Being aware of the sources of repugnance can only help make such discussions more productive, not least because it can help separate the issues that are fundamentally empirical—like the degree of crowding out of altruistic donations that might result from different incentive schemes compared to how much new supply might be produced—from areas of disagreement that are not primarily empirical.

Hopefully his new Nobel Prize should give that argument greater weight in the years ahead.

A patient receives a kidney in Johns Hopkins university in Baltimore. Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

Nicola Sturgeon and Tony Blair. Photo: Getty
Show Hide image

Nicola Sturgeon's SNP, like Tony Blair's New Labour, is heading for a crash landing

The fall of Tony Blair should be a set text for anyone wishing to know what happens next to the SNP.

If there was one thing the SNP and New Labour had in common, it was the hope. Both offered themselves as a burning torch of optimism to publics that had become tired of the same old gang running things in the same old way. Both promised a fairer, more equal society and a fearless embrace of the modern world with an appealing freshness and energy. The voters bought it: both won big, repeatedly.

The thing is, if you’re elected on a mandate to be different, you’d better be different. In many areas, for a long time, New Labour managed to be just that. The smiling PM with the huge majority pushed through radical policies, some of which even worked. Tony Blair’s methodology was so successful and so convincing that the Conservatives and the Lib Dems reshaped themselves in his likeness. Arguably, a form of New Labour won in 2010 and 2015.

But, as they say, it’s the hope that kills you. When the inevitable attritional realities of governing start to weigh, when you make, as you will, bad decisions, when the list of enemies grows long, when you’ve just had your time, you’ll fall like all the rest – only, when you’ve soared so close to the sun, you have that much further to plummet.

The fall of Blair and of Labour should be a set text for anyone wishing to know what happens next to the SNP. Sunday night’s debate between the Scottish party leaders was, I think, a foretaste of what’s coming – a public that until recently was politically and emotionally invested in the Nats is growing restive. In time, this will turn to disenchantment, then anger, then revenge at the ballot box. This is the unbreakable cycle of democratic politics.

Some of us have warned since the start that the SNP had over-promised and could only under-deliver. Its raison d’etre is independence; everything else - literally everything else - is just another brick to build the path. And so education reform cannot be either radical or unpopular, even if it needs to be so to work, because the SNP cannot afford to alienate teachers or the teaching unions or parents. Bricks, you see. Same with the NHS and doctors and health unions and patients. All the separatists have done – all they could have done, given their nature - is deploy the rhetoric of the radical while in reality body-swerving hard choices and conflict at any cost. And where they have found themselves taking flak, they’ve pointed south to Westminster: "it’s no’ our fault, it’s theirs".

But voters show signs of wearying of the predictable blame game and waking up to the time-limited strategy of show-over-substance. Middle Scotland is either ignored or maligned by the middle-class socialists who drive the nation’s political debate, but it is where elections are won. The SNP has secured the support of enough of these people to win every recent election in style, but somewhere along the way the party seems to have forgotten this was a mandate not for independence, but for good government. Ten years in to SNP rule, each new audit of public services seems to wail like a warning siren – things aren’t just not improving, they’re getting worse. The SNP is not keeping its part of the deal.

So, during Sunday night’s debate it was Nicola Sturgeon, not Ruth Davidson or Kezia Dugdale, who found herself in the audience’s cross-hairs. It will have been a strange experience for a woman more used to public adulation and a clamour for selfies. There were the teachers, who complained about the damp squib that is the Curriculum for Excellence, the SNP’s flagship education policy; who pointed out that a fifth of primary pupils are leaving without basic literacy and numeracy skills; and who warned that lowering the standard of exams in order to push up the pass rate was not a mark of success.

Then there was the nurse who said she had been forced to use a food bank (the existence of which has been used repeatedly by the SNP as a stick with which to beat the Conservatives and Westminster): ‘I can’t manage on the salary I have [which is set by the Scottish Government]. You have no idea how demoralising it is to work in the NHS. Don’t come on your announced visits, come in in the middle of any day to any ward, any A&E department and see what we’re up against.’ She delivered the evening’s killer line: ‘Do you think your perceived obsession with independence might actually cost you… in this election?’

The list of reasonable criticisms is growing and will grow further. The ideological obsession with free university tuition for Scottish students is increasingly seen as a sop to the better-off, while in England the fee-charging regime has seen the number of students coming from poorer families climb. Ms Sturgeon’s demand for a quick second independence referendum, when a worried middle Scotland was focused on what Brexit might mean for its future, was tone deaf.

The SNP has another problem (one that New Labour, for all its flaws, didn’t face): its doctrine of infallibility. The Nats’ constitution explicitly prohibits its elected members from criticising the party, its policies or each other. While total unity is useful when you’re on the climb, it starts to look bonkers when the cracks are showing. Allowing public self-criticism, far from being a sign of weakness, is a necessary vent for inner tensions and a sign to voters that a political party is something more than a cult.

That ‘cult’ word has long dogged the SNP and its supporters. The party has tried hard to normalise its electoral appeal while keeping the flame of independence burning bright, but it has been a difficult balancing act. The pro-independence mob is an ugly thing when it is unleashed (and it has suited the leadership to open the cage at times). Claire Austin, the nurse who criticised the First Minister on Sunday, has found herself at its mercy. Immediately after the debate, the Nats briefed (wrongly) that she was the wife of a Tory councilor. The SNP branch in Stirling said Tebbitishly that if she was having to use food banks "maybe she needs to tighten her belt a bit more?" Joanna Cherry, a QC, MP and the SNP’s Home Affairs spokesperson, was forced to publicly apologise for spreading "Twitter rumours" about Ms Austin.

The ravening horde has largely kept its head down since the 2014 independence referendum, but we now see it hasn’t gone away - it is not enough for the SNP’s critics to be debated, they must be destroyed. This isn’t the behaviour of a normal political party: it’s the behaviour of a cult.

I might be wrong, but I have a feeling that when the SNP does fall it will fall quite quickly. Its belief in its infallibility, its inability or unwillingness to do self-deprecation or apology, will increasingly aggravate voters. There is nothing to suggest the current public policy failings will be addressed, and plenty of signs that things will get worse. How, then, do you arrest your fall?

The SNP offered hope and promised it was different, and the voters believed. The sense of betrayal could make for a very hard landing indeed.

Chris Deerin is the New Statesman's contributing editor (Scotland). 

0800 7318496